Induction unit for air conditioning



March 5; 1957 R, D, LUM 2,783,979

INDUCTION UNIT FOR AIR CONDITIONING INVENTOR Roberc DBlum ATTORNEYSMarch 5, 1957 BLUM INDUCTION UNIT FOR AIR CONDITIONING 2 Sheets-Sheet 2Filed March 2, 1955 INVEN'IYOR Robert D'Blum BY @od Jun ATTORNEYS UnitedStates Patent 2,783,979 INDUCTION UNIT FOR AIR CONDITIONING Robert D.Blum, York, Pa., assignor, by mesne assignments, to Borg-WarnerCorporation, Chicago, 11]., a corporation of Illinois Application March2, 1955, Serial No. 491,578 7 Claims. (Cl. 257-137) This inventionrelates to heating, ventilating and air conditioning, and particularlyto room units containing a heat exchanger and jet means operated by whatis called primary air" and serving to induce a flow of room air, calledsecondary air, into heat exchanging contact with the heat exchanger.

The inductive heat exchanger of the prior art is customarily a finnedflat coil extending across an entrance opening leading to the interiorof the unit through its front. The secondary air enters the unit,exchanging heat with the coil and then mixes with the primary air withinthe unit. The resulting mixture flows back to the room usually throughthe top of the unit.

The advantages of such a unit are comparative silence, simplicity ofconstruction and the facts that the primary air is sufiicient inquantity for ventilation and may be conditioned at a central plant anddistributed to the various units through duct work.

The disadvantages encountered heretofore are poor inductive effect (lowratio of secondary air to primary air) and unsatisfactory heat exchange.Attempts at improvement involving changed spacing of fins, or use of twosuperposed coils with fins in common (either or both) have not solvedthe problem. They had no significant effect. Improved nozzlearrangements have been tried, but only one (devised by this applicant)is known to make significant improvement, and there is a demand forsomething even better.

The whole trend of the art has been and still is to keep the unit low,so it can be set under any window, and shallow so it would not projectfar into the room. Added capacity had to be attained by increasinglength with corresponding increase in consumption of primary air.

Applicant discovered that by discharging the primary air through a slotnozzle, or a plurality of nozzles into a narrow space between two spacedand rather thin finned coils, and so that the resulting jet stream orstreams approximately bisected the interval between the coils, he couldgreatly improve performance. The coils may be parallel, or they may besplayed outward with reference to the direction of primary air flow. Theuse of two coils accounts for the major portion of the gain, and thesplayed arrangement for a minor portion. Thus two parallel coils wouldbe preferred when space considerations are paramount. The splayedarrangement would be used when the utmost performance is desired.

The rear coil must be spaced from the wall to afford an entrance pathfor the secondary air. As successfully used, the coils are only one tubedeep in the direction of secondary air flow. They can be adequatelyfinned and can have about twice the total effective surface used inprior art units.

Remembering that doubling the surface in the old single sideconstructions led to no significant improvement, the fact that the newsymmetric construction with two thin coils greatly improves heatexchange and by improving the efiiciency of the nozzle markedlyraisesthe ratio of secondary to primary air, is truly remarkable, and iscontrary to the indications afforded by prior tests.

This improved action is traceable to at least two causes. Twosubstantially equal streams of secondary air enter in nearly oppositedirections and merge with the primary air jet or jets, so that themerging flows have a symmetrical pattern which inherently tends tocenter the merged stream between the opposed exchangers. There isconsequently less frictional retardation of the merged stream as itflows between the finned exchangers and less tendency to dissipateenergy in eddying.

The secondary air derives propulsive energy from both sides of thepropulsive jet so that a larger proportion of the jet energy iseffectively applied and so that the tendency to cause eddying is less.This is easier to appreciate where the nozzle is a long slot discharginga sheet of air which bisects the interval between the heat exchangecoils, but the effect is not limited to this type of nozzle. Every jetstream has at least two opposite sides, and the invention renders botheffective.

By using two thin coils set parallel instead of one coil as heretofore,and by carefully choosing the interval between the proximate faces ofthe fins (into which interval the nozzles discharge) it is possible tohold the total thickness of the double sided coil unit to former singleside dimensions, so that the only necessary increase is the smallinterval needed behind the rear coil to afford an inlet path forsecondary air flowing to the rear coil. Where the angle between the twocoils is moderate, the splayed coil arrangement is nearly as compact andthe entrance path to the rear coil is better.

Since the rear coil is comparatively inaccessible, an entrance filterfor all secondary air is considered necessary but the improvement ininductive effect is much more than enough to overcome the resistanceoffered by commercially available filters. The use of throw-away filterssimplifies maintenance and prevents the generation of odors.

Several embodiments of the invention which are intended to be exemplarywill now be described by reference to the accompanying drawings.

Figure 1 is a vertical longitudinal section on the line 11 of Figure 2,and showing a parallel coil arrangement.

Figure 2 is a vertical section on the line 2-2 of Figure 1.

Figure 3 is a perspective view of a nozzle plate having a single longnozzle slot.

Figure 4 is a perspective view of another type of nozzle plate.

Figure 5 is a view similar to Figure 2, but showing a splayedarrangement of the coils.

Figure 6 is a perspective of the unit shown in Figure 5 omitting thedecorative casing.

Refer first to Figures 1-3.

The main housing of the unit is a rectangular shell having front andrear panels 5 and 6, end panels 7 and 8 and a bottom 9. The top is open.A nozzle plate 11 which is fixed in place divides a pressure plenum 12from an induction space 13 and carries an upwardly directed nozzle 14with a continuous discharge slot 15.

Instead of the nozzle plate 14 it is practicable and often desirable touse a nozzle plate 16 such as is shown in Figure 4. This has a pluralityof transverse nozzles diversified as to height, long nozzles 17alternating with short nozzles 18. All of the nozzles 17 and 18 areshown as of the elongated slot type and, as shown, the slots extendtransversely. A conditioning unit of the single coil type having suchnozzles is described and claimed in my application Serial No. 393,559,filed November 23, 1953, now abandoned.

The connections 21 are for supplying primary air to the plenum 12.Either one of the connections 21 is plugged and the other is connectedto a duct conveying primary air under suitable pressure.

This primary air discharging from slot 15 induces inward flow of roomair through the inlet apertures 22 in front panel and 23 in rear panel6. The air so entering exchanges heat'with hot or cold heat exchangemedium (water) flowing through flat coils 24 or 25 which are finned, asindicated at 26 and which overlie the openings 22 and 23. Supply anddischarge connections 30 for the coils are shown. The coils 24 and 25may be connected in parallel with each other, or in series, in the watercircuit of the conditioning system as engineering considerations maydictate.

The coils are suspended on the front and rear panels by slot-engagingflange-like hooks 27 and overlie drip troughs 28 intended to collectdrip. water which may condense from the air in summer. Drain connectionsfor drip water are indicated at 29.

The functional inductive unit, above described, is enclosed in anornamental casing having a front 31, back 32, ends 33 and top 34. Thetop 34 is apertured to receive a flanged tubular member 35. The tubularportion of member 35 fits the upper end of the main housing and theflange 36 rests on top 34.

The tubular member 35 leads air to the room and is provided withdischarge louvers 37. The front 31 of the ornamental casing is providedwith louvers 38 practically from end to end. Since the ends 7 and 8 ofthe main housing and the front and back panels 5 and 6 thereof arespaced from the ends, front and back of the ornamental casing, room airentering through the louvers 38 can fiow freely to openings 22 and 23. Afilter 39 is mounted behind the louvers to remove dust from the enteringroom air.

The modified form shown in Figures 5 and 6 is basically similar to theform shown in Figures 1 to 3 inelusive and for that reason it ispossible to use the same reference numerals to designate the same parts.Thus, components which are unchanged are given the same referencenumerals used in Figures 1 to 3. Where there are significantdifferences, the numeral is used with a subscript a.

The pressure plenum 12 is essentially the same in the modifiedconstruction, but the induction space 13a enlarges upwards. The nozzleplate 11 is essentially the same as that shown in Figures 2 and 3. Theend plates 7n and 8a are given a flared configuration in their upperportions. This is clearly apparent in Figure 6. The front and rearplates 5a and 6a are formed in two parts so offset that the upper partswhich define the entrances 22a and 23a for secondary air have thedesired flaring arrangement. The coils 24 and 25 are not materiallychanged and each has fins 26. They are mounted against the outer facesof the upper portions of the plates 5a and 5a and conform dimensionallyto the openings 22a and 23a. The drip troughs 28a overlie the marginalportions of the nozzle plate 11 as best shown in Figure 5 and haveoffset drain connections 29a as best shown in Figure 6.

The decorative casing is not materially changed, but extends slightlyfurther outward from the wall. The entrance louvers 38 and the filter 39conform to the similarly numbered parts in Figure 2. The connections 30for the heat exchange liquid are essentially the same as those shown inFigure 1. The two heat exchange coils may be connected up either inseries or in parallel as engineering considerations may dictate.

While the single slot nozzle plate shown in Figure 5 is preferred, it istechnically possible to use the type of nozzle shown in Figure 4 withthe construction illustrated in Figures 5 and 6.

Thus four specifically different arrangements have been indicated, i. e.either of two specifically different coil arrangements with either oftwo specifically diiferent forms of nozzle.

As stated, the embodiments above described are given as examples of theinvention. Modifications within the scope of the claims arecontemplated.

What is claimed is:

1. The combination of a generally rectangular enclosing casing having ineach of two opposed faces an inlet aperture and in a third face .an exitaperture; two fiat heat exchange coils each substantially coextensivewith and extending across a corresponding inlet aperture; said coilsbeing spaced apart to aiford an interval forming' a iiow path to saidexit aperture; connections for circulating heat exchange medium throughsaid coils; and means for directing flow-inducing air through saidinterval towardsaid exit aperture comprising nozzle means directedtoward the exit aperture and mounted at that margin of said intervalwhich is remote from the exit aperture; and connections for supplyingair under pressure to said nozzle means.

2. The combination defined in claim 1 in which the coils aresubstantially parallel.

3. The combination defined in claim 1 in which they coils are at anacute dihedral angle to each other and the nozzle is substantially atthe apex of said angle.

4. The combination defined in claim 1 in which the coils are at an acutedihedral angle to each other and the nozzle is substantially at the apexof said angle, and comprises means defining a slot which is parallelwith said apex and serves to discharge the primary air in a plane sheetwhich substantially bisects said dihedral angle.

5. The combination of a generally rectangular enclosing casing having ineach of two opposed faces an inlet aperture and in a third face an exitaperture, the entrance apertures being of similar proportions, andsubstantially equal in size; two flat heat exchange coils eachsubstantially coextensive with and extending across a correspondinginlet aperture; said coils being substantially parallel and spaced apartto afford an interval forming a flow path to said exit aperture;connections for circulating heat exchange medium through said coils; andmeans for directing flow-inducing air through said interval toward saidexit aperture, comprising a substantially continuous slot-nozzlecoextensive in length with and positioned substantially at that marginofthe interval which is opposite to said exit aperture, said nozzle beingpositioned to discharge along substantially the medial plane of saidinterval and toward said exit aperture; and connections for supplyingair under pressure to said nozzle.

6. The combination of a generally rectangular enclosing casing having ineach of two opposed faces an inlet aperture and in a third face an exitaperture; two fiat heat exchange coils each substantially coextensivewith and extending across a corresponding inlet aperture; said coilsbeing spaced apart to afford an interval forming a how path to said exitaperture; connections for circulating heat exchange medium through saidcoils; and means for directing flow-inducing air through said intervaltoward said exit aperture, comprising a manifold extending along thatmargin of said interval which is remote from said exit aperture;connections for supplying air under pressure to said manifold; and aplurality of parallel platelike nozzles lying in planes normal to theflat coils, fed with air by the manifold, and extending toward said exitaperture for different distances measured from the manifold, saidnozzles serving to direct flow-inducing air through said interval towardsaid exit aperture.

7. The combination defined in claim 6 in which short and relativelylonger nozzles alternate so that their points of discharge aredistributed over said interval.

References Cited in the file of this patent UNITED STATES PATENTS

